The use of inkjet printing in offices and homes has grown dramatically in recent years. The growth can be attributed to drastic reductions in cost of inkjet printers and substantial improvements in print resolution and overall print quality. While the print quality has improved drastically, research and development efforts continue toward further improving the print quality to achieve images having photographic quality. A photographic quality image includes saturated colors, high gloss and gloss uniformity, freedom of grain and coalescence, and a high degree of permanence. To achieve photographic image quality, the print medium must be fast drying and resist smearing, air, light, and moisture. In addition, the print medium should provide good color fidelity and high image resolution.
In order to obtain printed images that dry quickly and have good image quality, durability, and permanence, microporous inkjet print media with thermally laminated barrier layers have been developed. While lamination of the printed image provides very good image quality and permanence, the cost of producing the laminated images is increased due to the cost of the laminator and the additional supplies that are necessary. In addition, lamination produces haze and air bubbles, which become trapped, decreasing the image quality of the printed images.
Print media that are capable of producing images having photographic image quality are typically categorized into two groups: porous media and swellable media. Porous media generally have an ink-receiving layer that is formed from porous, inorganic particles bound with a polymer binder. An ink-jet ink is absorbed into the pores of the inorganic particles and the colorant is fixed by mordants incorporated in the ink-receiving layer or by the surface of the inorganic particles. Porous media have a short dry time and good resistance to smearing because the inkjet ink is easily absorbed into the pores of the ink-receiving layer. However, porous media do not exhibit good resistance to fade.
In swellable media, the ink-receiving layer is a continuous layer of a swellable, polymer matrix. When the inkjet ink is applied, the inkjet ink is absorbed by swelling of the polymer matrix and the colorant is immobilized inside the continuous layer. Since the colorant is protected from the outside environment, swellable media have greater resistance to light and dark/air fade than the porous media. However, the swellable media generally have reduced smearfastness and a longer drytime than porous media.